Loud-speaking telephone receiver



2: 3%. A. A. THOMAS LOUD SPEAKING TELEPHONE RECEIVER a Sheets-Sheet 1 Original Filed July 5. 1922 m. N .V m

April 8, 1 930 i A. A. THOMAS ,8

I LOUD sPmmycY TELEPHONE :RECEIVER Oi-iginal Filed July 3 1922 3 Sheets-Sheet 2 I v 6a i 614 8 April 8, 1:930. A. THOMAS I v ,812

Loun SPEAKING TELEPHONE RECEIVEI'R Original Filed July 3. '1922 5 Sheets-Sheet 5 uaa patented Apr. 8, l fi ADOLIPH ALEXANDER THOMAS, OF NEW YORK, NY.

LOUD-SPEAKING TELEPHONE RECEIVER Application filed July 3, 1922, Serial No. 572,730. Renewed August 10, 1929.

ment as a unit. This obviates the danger of any disarrangement of-the adjusted parts in mounting them Within the outer casing of the loudspeaker.

Another feature of my invention provides for completely cutting off the space containing the electromagnetic mechanism from the acoustic chamber above the diaphragm, thereby improving the quality of the reproduction;

Furthermore, my invention permits the use of two diaphragms operated by a single armature for producing sound. of increased volume. The vibrations of the two diaphragms are preferably conveyed to a com mon outlet in the casing of the instrument. I

The foregoing andlother advantages of my invention will be understood from a detailed description of the accompanying drawings,

in which Fig. l is an interior View of a telephone receiver embodying various features of my invention, certain parts being shown in section forclearness; I

Fig. 2 is aview at right angles to Fig. l, certain parts being broken away for clear; ness;

Fig. 3 is a plan View of the construction.

shown in Figs. 1 and 2, with the diaphragm and supporting casting-indicated in dotted lines Fig. 4 is a side view, partly in cross-section, of a telephone receiver having a circular magnet;

Fig. 5 is a plan new of the construction shown in Fig. 4:, with the supporting casting for the'diaphragm broken away for clear ness' 6 is a fragmentary detailed viewon an enlarged scale to show more clearly the mounting of the diaphragm and the adjust- .ture

able connection with the armature, this particular form of mounting and connection being merely illustrative;

Fig. 7 shows a telehpone receiver embodying two diaphragms connected to the arma- .Fig. 8 is a cross-section approximately on line 8-8 of Fig. 7, on a somewhat enlarged scale; I

Fig. 9 is abottom sectional view approximately on line 9.9 of Fig. 8, looking in the direction of the arrows;

Fig. 10 is an enlarged fragmentary vieW showing a convenient way of connecting the diaphragm rod or wire to the armature;

Fig. 11 is a cross-section view ofthe connection shown in-Fig. 10; and

Fig. 12 is a View similar to Fig. 11, showing the rod or Wire screwed into the armature.

The loudspeaker shown in Figs. 1, 2 and 3 has a U-shaped magnet, while the construction shown in Figs. 4 and5 employs a circular magnet. 11 Figs. 7, 8-and 9, I have shown a loudspeaker embodying two diaphragms for producing increased volume. I Wlll now describe these illustrative embodiments in detail.

Refering first to Figs. 1, 2 and there is onbolts 2. To accommodate the screws 2, the

' base of the magnet may be widened, as indicated at 3 in Figs. 2 and 3. The base member 1,usually in the form of a circular plate, may be of non-metallic material, such as porcelain, fiber, and the like. To the legsof magnet M are secured divided or bifurcated pole pieces, one of which consists of members 4 and 5, and the other of "members 6 and 7 The members or bifurcations 4 and 5 may be assumed to. constitute the north pole, and the members or bifurcations 6 and 7 may be considered as the south pole. The polar faces of pole piece N are separated by an air. gap 8, andthe polar faces of pole piece S are separated by 'a similar air gap 9. The main body a of the permanent magnet- M is of hard steel and the pole pieces are preferably of soft iron, either solid or laminated. The polar members 4, 5, 6 and 7 are secured to the body of the magnet in any suitable .way, as any electrician understands. An armature .A

mounted in operative relation to 'the bifurcated pole pieces N and S. This armature is shown in the form of a Hat bar pivoted at 10 between a pair of non-magnetic supporting plates 11, which may conveniently be secured to polar members 5 and 7, as by' screws 12 or otherwise. The precise mounting of the armature is immaterial, provided it is maintained in proper operative relation to the pole pieces of the magnet.

In Fig. 1, armature A is shown extending into the polar air gaps 8 and 9, and is normally in a position practically midway of the adjacent polar faces. i' r1*nn1t ure A preferably of soft iron, like the'pole pieces.

On magnet M-is mounted a non-ma netic frame indicated as a whole by F. This frame may conveniently be cast'in asingle piece of suitable non-magnetic metal, such as aluminum, bra ss and the like. The main portion of frame F consists ofa ring 13from which extends a pair of legs 14. The arrangement and spacing of'legs 14 are such that they fit against the legs of magnet M to which they are secured in any practical way as by'means of screws 15 or otherwise.-

Ring 13 is provided with-a recess 16 in which is fitted a diaphragm 'D. A suitable screw cap 17 holds the diaphragm rigidly' clamped in place. If desired, a non-metallic washer 18 may be placed on each sideof the diaphragm, as best shown in the enlarger fragmentary view in Fig.- 6. The washers 18 may be of paper, fiber or other suitable material. In Figs. 1 and 6, the downward movement of screw cap 17 is limited by a shoulder 19 on ring 13. Itis immaterial how diaphragm D is supported, provided it is free to vibrate. Diaphragm D is operatively connected to armature A by a rod or wire 20, preferably of non-magnetic material. The inner end of rod 20 is secured to the armature at or near one end thereof in any suitable manner. For instance, in Figs. 10 and 11, the inner end 21. of rod 20 is bent at right angles to the main portion of the rod: and

- for connection with diaphragm D. Referring 'to Fig. 6, it will be seen that the outer end of rod' 20 is screw-threaded'at 23 and'passes centrally through diaphragm D. It is preferable that the connection between the diaphragm and armature be-adjustable, and for that purpose I have shown two pairs of nuts 2 4.and 25 on rod 20 at oppositesides of the diaphragm. By means of these nuts, the distance between the diaphragm and armature 'loose.

may be adjusted to the precise length required in-any particular case. The use of double nuts prevents the connection from becoming Any other practical connection between armatureA and diaphragm D may be employed. The diaphragm is preferably made of some suitable non-magnetic material, such as aluminium, mica, wood, composition, or any other vibratory material capable of responding freely to the vibrations of the armature.

The poles of magnet M are provided with coils C and C connected in series, as indicated diagrammatically by a conductor 26. The other end of coil C is connected to a binding post 27 by a conductor 28, and the other end of coil C is connected to a binding post 29 by a conductor 30. Although I have I shown the coils C and C on the diametrically opposite polar members 5 and 6, it is obvious that they might be mounted on polar members 4 and 7. The coils G and C, which in etl'ect' constitute a single coil, are connected in a suitable circuit of variable current, as a telephone circuit, and the current variations produce vibration of armature A in a manner well understood by those skilled in the art. The movements of the armature are transmitted to the diaphragm. Instead of a permanent magnet, I may use an electromanget energized by a source of constant voltage or current to maintain a practically constant magnetic field, like a pernranent magnet. In the broader aspect of my invention, any other practical electromagnetic mechanism may be used to operate the acoustic diaphragm.

The mechanism of the loudspeaker above described may be enclosed in an outer casing, such as shown at 31 in Figs. land The lower edge of casing 31 fits snugly to base plate 1 and may be provided with a tubular extension 32 adapted to receive a horn or other sound-directing device. In order to accommodate the outside conductors leading to binding posts 27 and 29, the lower edge of casing 31 has a pair of slots 33', one ol which is shown in Fig. 1. Casing 31 is preterably so shaped in its upper portion as to provide a sound chamber 34 which is closed to the lower portion of the casing. If desired, a ring 35 of felt or similar material may be interposed between screw cap 17 and the casing.

In'the form of loudspeaker illustrated in Figs. 4 and 5, there is a permanent magnet M in the shape of a ring suitably securedto or set into an insulating base plate 236. For simplicity I have shown base plate 36 formed with a recess 37, in which the circular magnet M is rigidly held by screwthre'ads 38 or in any other convenient way. By setting the permanent magnet M. which is naturally a heavy steel body, into a recess I in the non-metallic base plate 36, the posillll series, aremounted on bifurcations 42 and.

weenie tion of the magnet is lowered and the stability of the entire structure is thereby increased. Magnet M is provided with a pair of extensions 39 and 40. To extension 39 are secured polar members 41 and 42, and to extension 40 are fastened similar members 43 and 44. Members 41 and 42 may be considered as the north pole N of the magnet and members 43 and 44 as the south pole S. The polar members or bifurcations 41, 42, 43 and 44 are secured to the extensions 39and 40 by any practical means, such as screws 45. Coils C and 0 connected in 43, respectively. The free end of coil C is connected to a binding post 46 by a conductor 47, and-the free end of coil C is connected to a binding post 48 by a conductor 49. Outside conductors 50and 5'1 lead to binding posts 46 and 48 through channels '52and 53 formed in the insulating base plate 36,.

Armature A is pivoted at 54 and mounted in operative relation to pole pieces N and S of magnet M. For the sake of convenience, I have shown armature A supported between a pair of non-magnetic plates'55 secured to polar members 42 and "44, similar to armature A of Fig. 1.

A non-magnetic frame, indicated as a whole by F, is mounted on the circular magnet "M'. For this purpose, frame F has a plurality of legs 56, so spaced and arranged as to fit on the upper circular edge of the magnet to which they are secured by any; suitable fastening means, such as screws 57. The upper portion of frame-F consists of a ring 58-adapted to receive a diaphragm D, which is held in place by a cap 59, or other-- wise. Diaphragm D is operatively connected to armature A- by a rod or wire 60. In-

' asmuch as this connection is the-same as that shown in Fig. 1, what I have previously stated in detail about the adjustable connection between armature A and diaphragm D may be considered as applying to armature A and diaphragm D, so as to obviate unnecessary repetition. I

The working parts of the loudspeakershown in Figs. 4 and 5 are preferably enclosed in an outer casing, indicated as a whole by 61, which is suitably fastened to base plate 36. A felt or similar washer 62 is preferably interposed between the casing and cap 59. Casing 61 may have a tubular extension 63 for receiving a horn or other sound-conveying device. r

One of the advantages of my invention lies in the fact that it permits the use of two diaphragms to be actuated by a single armature, thus increasing the volume of sound. In Figsf7, 8 and 9, I have shown a loudspeaker employing two diaphragms so arranged that the sound vibrations thereof are conveyed to a common outlet.

support 64 is mounted a circular permanent magnet M provided with polar members or extensions 69, 7 O, 71 and 72, constructed and arranged as shown in Fig. 9. Members 69 and 7 O constitute one pole ;piece (say, the north pole), and members 71 and 7 constitute the other pole piece of magnet M Ve thus have bifurcated pole pieces in which the respective polar faces are separated by air gaps 7 3 and.74, similar to the pole pieces in Figs. 1 and 4. It will be observed that the pole p eces 6970 and 71-72 a're arranged in a plane substantially at right angles to the plane of the circular body portion of magnet M similar to the pole'pieces of the circular magnet -M in Fig. 4. The pole pieces are secured to magnet M 'by screws 75 or in any other ;way.. Coil C is mounted on polar member 69, and coil C is mounted on polar member 72. These coils are connected in series by a conductor 76, as indicated in'Fig. 8.

.The free ends 77 and 78 of the coils lead to suitable binding posts or terminals (not shown) for connecting the loudspeaker in the receiving circuit. Magnet M has an armature A pivoted at 79 between a pair of non magnetic plates 80, which may conveniently be secured to polar members 70 and 72, sim-- as to be attachable to the circular body portion of the magnet itself. For this purpose, frame F is formed with legs 81 and frame F with legs 82. These legs are arranged to fit against the opposite sides of magnet M2, to which they are secured in any suitable way,

as by screws 83 or otherwise. The frame or casting F is provided with a. ring84, and casting F has a similar ring 85. On ring 84 is seated a diaphragm D held in place by any suitable means,such as a screw cap 86.

.The frame or casting F is formed with a ring 87. which supports a diaphragm D by means of a screw cap 88 or other clamping arrangement. Diaphragm D is connected ,to one end of armature A by a link 89, and diaphragm D is connected to the other end of the armature by a link 90. These connections between the diaphragms and armature A are preferably adjustable, as previously described in detail in connection with Fig. (i, or in any other practical way.

It will be clear from the foregoing that as the armature A vibrates in accordance with current variations in coils C" and C as those skilled in tlieart will understand, the diaphragms D and D vibrate in synchronism with the armature and produce soundwaves which are additive in their effect. That is to say, the ultimate acoustic effect of the two dia'phragms is practically double that of a single diaphratun. 4 If desired,the vibrations of diaphragms D- and D may be conveyed to a common outlet. For this purpose, I provide sound-con veyors 91 and 92. Sound conveyor 91 ter-- minates at its inner end in a conical enlarge- .ment 93, which tits over'the circularope'ning 65 of casing 64. Similarly, sound conveyor 92 is formed at its inner end with a .conical enlargement 9-l adapted to fit over the circular opening 66 of casing 64. Members 91 and 92 are preferably removable from casing 64 to permit ready access to the diaphragms and other parts. If desired, a ring 95 of felt or other suitable material may be interposed between the screw caps, which elamp'the diaphragms in place, and the adacent wall of the conical sound-conveyor. The.sound-conveying members 91 and 92 curve upwardly and outwardly, and are con- .lected tot-nbular extensions 96 and 97 of a sound-conveyor indicated as a whole by Y. This part may conveniently be cast as a sin: gle piece. The curved tubes 9192 -and 9697 are so shaped and spaced that they snugly fit into each other, so that they can be connected and separated with ease. These separable joints are indicated in Fig. 7 at '98 and 99. Casting Y has an outlet opening 100 projecting outsideof casing 68 and adapted to receive a horn or other sound-conveying device. The inner walls of opening 100 may be madeslightly conical to facilitate the attachment of a horn or similar member.

. It will be seen from the foregoing th'atI have providedfa telephone loudspeaker of a high degree of sensitiveness and capable of producing, sounds of considerable volume."

The specific constructions which I have shown and described are merely for the purpose of' illustrating and, explaining the various features of'my invention and are not to be considered as restrictions .or limitations. Obviously, the loudspeaker of my invention may be physically embodied in other forms than those herein set forth. In order to promote clearness in the drawings, I have not attempted to present the exact relative proportions of-the parts, but have shown the different parts rather spread out and more separated than would be required in actual praczontally in a relative sense 0nlythat is, to

bring out the iigl1tangled relation of those parts. Obviously, if the instrument is so placed that thefdiaphragm or daphragins are horizontal, the armature vibrates vertically.

What I claim is:

1. In a telephone receiver, the combination of a base, electromagnetic mechanism mounted on said base, said mechanism'ineluding a circular magnet, a nonmagnetic frame consisting of a ring having integral legsprojecting radially therefrom, said legs terminating in circularly arranged extensions adapted to fit against the annular body portion of said n'iagnet, means engaging said extensions for fastening said legs to said magnet, the parts of said mechanism being held together independently of said frame, and a diaphragm mounted in said ring and operatively connected with said mechanism.

2. In a telephone receiver, the combination of a base, a magnet mounted on said base, said magnet comprising a circular body portion providedwvdh polar projections, a vibratory armature and a coil operatively associated with said polar projections, a nonmagnetic frame having legs secured to the circular body portion of said magnet, and a diaphragm mounted in .said frame and 0peratively connected with, said armature.

3. In a. loudspeaking telephone receiver, a supporting-base, a casing mounted on said base and supported thereby, a magnet secured to said base, said magnet being provided with pole pieces, a non-magnetic frame comprising a ring and legs projecting therefrom, means for fastening said legs to said magnet, a pivoted armature operativelyassociated with pendently of said casing, and means for operatively connecting said diaphragm to one end of said pivoted armature.

4. In a loudspea'king telephone receiver, a supporting base, a'casing mounted on said base and supported thereby, a self-sustained magnet secured to said base, said magnet being provided with pole pieces,a non-magnetic frame mounted as a unit in fixed relation to said magnet, fastening devices for rigidly holding said frame in position, ayibratory i tening devices for rigidly holding said frame armature operatively associated with said pole-,p1eces, means independent of said frame for supporting said armature, a coil to cause in position, a vibratory armature op'eratively associated with said pole pieces, means independent of said frame for supporting said armature, a coil to causev vibration of said armature, means for holding said coil in position independently of said fastening devices, and a casing or cover mounted on said base and supported thereby, said casing comprising a cylindrical base section and a conical extenslon opposlte said dlaphragm, said conical extension being arranged to constitute a sound conveyor for said diaphragm.-

6. In a loudspeaking telephone receiver, a supporting base, a magnet mounted on said base and having a vibratory armature, 31 non magnetic frame mounted m fixed relat on to said magnet and comprising a supportlng ring, a casing mounted on said base and com prising a main section and a conicaliextension open to the-'outer air, a diaphragm rigidly mounted on said ring and held thereon independently of said casing, said conical extension beingarranged to engage saidring-andthereby forming opposite said diaphragm a sound-conveying chamber that is practically closed to the magnetic mechanism operating the diaphragm. v I

7. In a telephone receiver, a magnet having a pair of upstanding limbs, opposite pole pieces projecting inwardly from said limbs silbstantially in alignment with each other.'a support comprising a pair of non-magnetic plates secured to said pole pieces'at opposite sides thereof, an armature centrally pivoted on said support and extending lengthwise from one pole piece to the other, electromagnetic means for producing vibration of said armature about its pivot, and a diaphragm connected to said armature. i

8. In acoustic apparatus,a base, a magnet mounted on said base in an upright position,

pole pieces on said magnet, a vibratory ar'mature operatively associated with said .pole pieces, a pair of non-magnetic frames secured to the opposite sides of said magnet, a diaphragm mounted in each frame, and means for connecting said diaphragms to said armature. I

' 9. In acoustic apparatus, a base, a magnet mounted on said base in an upright position, pole pieces on said magnet, a vibratory armature operatively associated with said pole' pieces, a non-magnetic frame at each side'of said magnet, adiaphragm carried by one of said frames and connected to one end ofsald armature, and an acoust c member mounted in the otherframe andconnected to 'theother endof said armature. 10; In a. telephone receiver, the combination of a supporting base, a magnet rigidly mounted on said base, and having pole pieces extending toward each other, an armature operatively associated with said pole pieces, a coil arranged to cause vibration of said armature, a frame having le'gs removably secured to said magnet, said magnet being structurally independent of said frame, and an acoustic diaphragm carried by said frame and connected'with said armature, said frame and diaphragm being removable from said magnet as a unit without disturbing the mounting ofsaid coil and said armature.

tion. of a supporting base, electromagnetic 11. Ina telephone receiver, the combina mechanism mounted on said base, a-anon magnetic frame mounted in fixed relation to ,SiLld magnet, a casing mounted on said base and having a conical extension which'forms a sound chamber provided with an outlet, and.

a diaphragm carried by said frame in said cham -mechanism, said frame and diaphragmrforming a closed partition in said chamber.

12. In a telephone loudspeaker, the combination of a casing. a frame arranged to diyide said casing transversely into an'outer chamber and an inner chamber, a diaphragm carried by said frame, said diaphragm and frame constituting a partition for closing off the inner chamber from the outer chamber,

erand operatively connected with said electromagnetic mechanism in said inner chamber for operating said diaphragm, and asound passage in said outer chamber.

13. In' a telephone receiver, the combination of a casing consisting of a cylindrical section anda conical section, a circular frame arranged to dividesaid casing into a conical chamber and a cylinder chamber, a diaphragm' carried by said frame, said-diaphragm" and frame constituting a partition for closing off the conical chamber from the cylindrical chamber, electromagnetic mechanism in said cylindrical chamber for oper* ating said diaphragm, and a cylindrica extension on said conical section opposite said diaphragm to form a sound passage and con- U necting means for an amplifier.

14. In a telephone. receiver, the combination of a casing having a conical section, a ring in said section, said ring being arranged to bear against the inclined inner wall of said section, a diaphragm carried by said ring and forming therewith a closed partition across said conical section, electromagnetic mechanism mounted in said casing in a space acoustically separated from said conical section by said partition, and a sound openlng at the conveying end of said conical section.

.15. In a loudspeaker, a framework, a pair of diaphragms supported by said framework in upright position, a sound'tube extending laterally from one of said diaphragms, a mag net structure arranged between said diaphragms, a horizontally vibratoryarmature pivotally supported on said magnet structure independently of said diaphragms, a coil on said magnet structure for controlling said armature, and a pair of horizontally eXtending parallel links for connecting said diaphragms to different points of said armature.

16. In a loudspeaker, a base, a pair of ringshaped supports carried by saidbase and arranged eccentrically with respect to each other in substantially parallel relation, a diaphragm carried by each support, an electro-' magnetic structure between said diaphragms, said structure having a pivotally mounted armature arranged to vibrate in a plane substantially at right angles to the planes of said ring-shaped supports, means for supporting said armature independently of said diaphragrns. the axial centers of said diaphra'gms being-on opposite sides of the pivot point of said armature, and a pair of parallellink's attached at one end to the centers of said diaphragms and at the other end to said said magnet structure independently of said diaphragms, a pair of coils mounted on said magnet structure to control said armature, a second diaphragm supported on said base in upright position, and a pair of-links between said diaphragms and said armature for simultaneously operating the diaphragms, said links beingattached to said armature at opposite sides of its pivot point.

18. A loudspeaker comprising a cylindrical casing open at opposite ends, a base for,

supporting said casing in upright position with its axis substantially horizontal, a pair of oppositely arranged diaphragms mounted at the open ends of said casing in upright position, a rod secured to the center of each diaphragm and extending inwardly toward the casing, and electromagnetic mechanism supported in said casing between said diaphragms for simultaneously actuating the same, said mechanism including an upright magnet having vibratory means mounted thereon, the inner ends of said rods being connected to said vibratory means.

19. In a loudspeaker, a magnet structure having two pairs of spaced polar projections arranged to provide a pair of aligned airgaps, non-magnetic brackets fixed to said polar projections, a centrally pivoted armature arranged between said brackets and extending into said airgaps, a coil mounted. in operative relation to said polar projections to cause vibration of said armature, a pair of diaphragms mounted on opposite sides of said polar projections, and means for 'c01i necting said armature to said diaphragms.

2Q. In a telephone receiver, a magnet struc-' turehaving a plurality of pole pieces extending toward each other to form aligned airgaps, a pair of non-magnetic plates secured to said magnet structure in spaced parallel relation, an armature centrally pivoted between said plates in operative relation to said airgaps, electromagnetic means for producing vibration of said armature about its pivot, and a" diaphragm eonnectedto said armature. 21; In an'electromagnetio translating device, a magnet having pole pieces extending toward each other, a pair of non-magnetic plates secured to opposite sides of said-pole pieces and holding them in predetermined spaced relation, a vibratory armature mounted on said plates and arranged between the same in operative relation to said pole pieces, a coil associated with said pole pieces and armature, and means for attaching said pole pieces to said magnet.

22.'In an electromagnetic translating device, a magnet having pole pieces extending toward each other, non-magnetic plates secured to opposite sides of said pole pieces and holding them in predetermined spaced relation, a vibratory armature pivotally supported by said plates in operative relation to said pole pieces, a coil associated with said pole pieces-and armature, and means for attaching said pole .pieces to said magnet.

23.-In a telephone receive, a magnet havinga pair of limbs, opposite vpole pieces projecting inwardly from said limbs substantially alignment with each other, a support comprising non-magnetic plates secured to said pole pieces at opposite sides thereof, an armature pivotally carried by said support in operative relation to said pole pieces, electromagnetic means for producing vibration of said armature about its pivot, and a diaphragm connected to said armature.

ADOLPH ALEXANDER THOMAS.

Hetmmeme et eeklaeetmm. Patent No. 1,753,812, 7 t l GruteuiApri-l a, mum

' AW PH ALEXANDER THOMAS.

it is iiereby certitijed that enroi apiaeafsv in the: printed] specification of the aimvenumbered patent requiring cbrrectitm-as follows: Page 6, time 85, ciaim 2%,. strike out the weird "centrally"; and that the said Letters Patent siieuidi-lbe the ease in the Patent ifiee-.

readwith this correction therein that the same may center-mm the reconi 0i Signed andeeaie i this 3rd day at June, D. 1 30.5

v tip-t; Moore, (Seal) v Y Acting flemmiseiener'et Patents. 

